


as much as you need

by tealmoon



Category: Undertale (Video Game)
Genre: Aftercare, Alternate Universe - Swapfell (Undertale), Alternate Universe - Underfell (Undertale), Anxiety, Blood, Fluffyhoodies, Knifeplay, M/M, Masochism, Prejudice Against Monsters (Undertale), kink as coping mechanism
Language: English
Status: Completed
Published: 2018-09-19
Updated: 2018-09-19
Packaged: 2019-07-14 05:42:03
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,516
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16034150
Author URL: https://archiveofourown.org/users/tealmoon/pseuds/tealmoon
Summary: Sometimes Slim can only find peace at the edge of a knife, and Red is willing to wield it.





	as much as you need

Slim growled, impatient with Red’s preparations. Bare bones carefully cleaned, healing foods at the ready. A clean, gleaming knife laying out on a towel on the bathroom tile.

He knew Slim was more than ready to begin, but Razz would have his head if he rushed these things. And so would Boss, and Cash, and Blue, if he learned about it. It was hard not to be protective over Slim, no matter how breathlessly he begged Red to bleed him out and then fuck him until they were both covered in it. As hot as that was, he had to do this right.

“Are you ready, babe?” He lifted the knife up, soul already throbbing at the weight of it in his hand.

“Red, I’ve been ready for _hours_ ,” Slim whined, the words coming out shaky rather than teasing, and that felt like the knife being pulled on him. Slim was a sweet kid, no matter how much LV he had. All Papyrii deserved to have fucking fairy-tale Surface lives, without asshole humans trying to ruin their day, hissing slurs as he tried to pass. What sort of useless, waste of air human would start screaming at a monster because he asked to pet their dog?

It wasn’t even the human being an asshole that was the worst part. Slim’s voice had trembled at how he told Red how the dog had pulled forward to meet his reaching hand, how the human had dragged the poor dog away from him, its claws scrabbling at the sidewalk...

Back when Slim first suggested this to him, he thought that it would have been more fitting for the offending humans to be sliced up a little, not Slim. _He_ hadn’t done anything wrong. If he hadn’t seen for himself how Slim’s anxious shaking could go still under a whip or a knife, his eyelights reappearing out of empty sockets, fuzzy and relaxed, Red wouldn’t have understood how important this was. Yeah, it could get him going, but more importantly, it quieted the 24/7 panicky soundtrack Slim had running up in that skull of his.

“So, where do you wanna start?” He had a feeling Slim would want as much of his body carved up as possible, but still he had to ask. This was Slim’s party, after all.

“Ribs first.” Not a huge surprise there; he saved the ribcage for when he was feeling uniquely shitty. He ran the edge of the knife along his lowest rib, and Slim _growled_ at him, arching his spine up so his rib collided with the tip of the knife, the bone nicked and already trickling amber magic. “ _Get on with it_.”

So that was how it was going to be. No foreplay, no teasing, no dragging the dull edge over his femurs to get him worked up and antsy. That was fine with Red; Slim might have been shy in most other situations, but it was always welcome to hear him demand what he wanted. Planting himself on Slim’s bare lap, he leaned it and got to work. It’d leave him nearly as messy, which was why he had stripped down too, but they liked being that close.

Red really wasn’t the type to draw designs in Slim’s bones—his hands weren’t delicate enough for that, even on a wider canvas like his scapulae. If Slim wanted something beautiful, he could ask Razz for it. The most he could get from Red was plain, deep-cut lines, soon to be erased by healing, and a promise to not carve dicks into his bones. Luckily Slim didn’t want anything more than that. He moved up the ribcage without neglecting a single rib, a cut down the middle of each, as far away around as he could get without making Slim turn. His sternum was wide enough for several vertical lines, and he ended off there.

Slim couldn’t watch for long, his head falling back to gently knock against the bathroom tile, mouth gaping as he whined and moaned. They always did it in the shower so Boss wouldn’t nag about how hard it would be to clean up magic stains. Wrestling with a tarp would have been fucking annoying, so they did it where the mess could be rinsed away. And there was already plenty of mess, all of his ribs now leaking amber.

“More?” Slim nodded furiously. The answer didn’t surprise Red in the least, but it was better to confirm it before he dived in knife-first. He stretched out his right arm, ready for it to be mutilated too. The bones of his arms were hardened with scars and healed breaks, and while his ribs had split easily under the carefully sharpened knife, Red had to really put some effort into driving it into his humerus. For a guy like him, this sort of thing was a workout, to the point that he’d need to get rinsed off almost as much as Slim, for the sweat alone.

Slim thrust his left arm at him before he had pulled the knife out of the right, and that gave him pause. “Hey, look up for me?” At least someone had to be responsible here. Slim’s jaw had drooped down to his sternum, leaving a little smear of magic there, but he looked up, panting heavily and... eye sockets completely blank. “Mind giving pupils a try, puppy?”

And he did try, the blackness roiling around in there, a tiny spark in the left one that guttered out after a second. That was a reliable sign as any that he had bled out too much magic. Red didn’t have any harmful intent, so Slim’s HP was full, but that didn’t mean it was necessarily healthy. A relaxing blood-letting session wasn’t so relaxing if Slim had to take several days to recover from it.

“Yeah, you’re done for now. If you still feel shitty once you’ve recovered from this, we’ll do the rest.” He whined, eyes following the knife as Red reached around him to rinse and dry it off, then put it safely out of reach. No matter how much he practiced, his healing magic was average at best, so while one hand starting moving over Slim’s ribs, the other groped for the bottle of caramel that he had accepted was a typical feature on their grocery list now. With his dominant arm torn up, Red held it up to his mouth for him. This was the good stuff, monster-made, the bottle covered in painted symbols that were meant to make the healing stronger.

Slowly, his injuries knitted together, and it would have looked like it had never happened if not for the magical blood still covering both of them. Reaching around Slim, he turned on the faucet, adjusting it to a lukewarm trickle before reaching for the showerhead.

Slim was barely clean before he dragged Red into his arms, the showerhead clattering beside him. There wasn’t the insistent press of magic between their pelvises, so the kid probably didn’t want to fuck, unless he was in the mood for bone grinding. But it seemed to be a hug and nothing more.

Red batted at his arm, very lightly. Barely a tap. “Hey, none of that. No heavy lifting right after you’ve been healed. Are you really gonna waste all that work I did?”

“You hardly count as heavy lifting,” Slim rasped out. Despite the lack of a throat, his voice was wrecked from all the noise he had been making. Boss must have heard them—the acoustics in here were great—so he was pretty sure there was tea ready and waiting downstairs. By now, Boss had gone from genuine worry to being scandalized by their activities to acceptance, but he’d be put out if they let that tea go cold. He was trying to help too, in his own way.

“Need to get you dried off, though, and it’s kinda hard to do it like this. Can’t even reach the towel.” A spark flickered in Slim’s socket, trying to gather enough magic to pull the towel closer, but he couldn’t maintain it. “Ey, stop it! You’re gonna get extra bed rest if you pull stunts like that, you’re too drained.”

With a huff, Slim loosened his grip, letting Red squirm away and begin to dry them both off. “But is it bed rest with you?”

“Well, yeah, obviously. Guess that doesn’t make it much of a punishment.” He was careful not to towel too vigorously, mindful of how sensitive Slim’s bones would be after being mutilated and restored. Slim had to cling to the towel rack to stand up off the wet tile, shivering as Red knelt to reach his legs. By the time he was dry, he was steadier on his feet.

Maybe Slim could have been fine from there but Red liked the feeling of helping him get dressed, knowing he was taking care of him. Soon Red would get them both into bed, a mug of tea in hand’s reach and a plate of Boss-made dinner waiting when he woke.

**Author's Note:**

> Trying to remember how writing works, it feels like it's been a million years. Fuck September tbh, where's all my words.


End file.
